A three-layer HD DVD disc with enough room for about 7 hours of high-definition video is still under development and hasn't been submitted for approval to the DVD Forum, the standard's governing body, despite reports to the contrary, Toshiba said Thursday.

The disc, which has a capacity of 51GB, was first unveiled at the International Consumer Electronics Show (CES) in Las Vegas in January this year. It attracted much attention not just because it substantially raises the maximum capacity of an HD DVD disc but also because it beats that of the rival Blu-ray Disc format, albeit by just 1G byte.

In the last few days a number of Web sites and blogs have reported the format has been submitted for approval to the DVD Forum and some have said that approval has been received, but Toshiba says nothing of the sort has happened.

"We're puzzled ourself by where these reports came from," said Junko Furuta, a spokeswoman for the company in Tokyo. She said Toshiba hasn't made any further announcements about the disc since CES, and it wasn't submitted to any steering committees during this week's DVD Forum meetings in Tokyo.

When Toshiba first announced the disc in January, it said it hoped to get approval for the disc some time in 2007.

HD DVD and Blu-ray Disc are competing to become the de facto replacement for DVD for storing high-definition movies and other content. HD DVD is primarily backed by Toshiba, while Sony Corp. is the main backer of Blu-ray Disc. HD DVD can hold 15GB on a single disc, or 30GB on a dual layer disc, while Blu-ray Disc manages 25GB or 50GB on single or dual-layer discs respectively.

To fit 51GB on its prototype disc Toshiba added a third recording layer and increased the maximum storage capacity of each layer to 17GB.